TWC BioSearch
Discount Research Software Agent

Elemental Formula Calculator

Elemental Formula Calculator is a tool that quickly and easily calculates possible elemental formulae consistent with a given mass. Calculations that could take hours to perform manually can be completed within seconds by this program. EFC is not limited to the standard C, H, O and N calculations; rather, it supports a total of 79 elements including essentially any element that might be encountered in mass spectrometry. All elements have predefined mass and valences, but these values can be edited if desired. EFC supports accurate mass values, up to seven different elements per composition, and molecular weights up to 15,000.

Calculations can be carried out as simply as entering a mass value and clicking the ‘Calculate’ button. On the other hand, a variety of constraints can be entered to limit the range of possible results. For example, the screen below shows the results obtained for the analysis of mass 545 + 0.50 AMU, in which at least 20 carbon atoms were required, along with any number of hydrogens. Up to three nitrogen atoms were permitted, and exactly three oxygens and four chlorine atoms were stipulated for each composition. In addition, only valid molecular ions adhering to the ‘nitrogen rule’ with an unsaturation index (rings + double bonds) of at least two, but no more than 10, were allowed:

Three compositions were identified here that fulfilled these restrictions. The program will calculate and display up to 1,000 possible compositions.

Results can be sorted and displayed in order by molecular composition, or by increasing difference from the target mass. The results can be printed, or copied to the Windows clipboard for incorporation into other programs.

Clicking on any result will display the elemental composition, accurate mass, difference from the target mass, electron parity, and the unsaturation index for that entry.

(Requires Windows 3.1 or 95, 98 or NT).
 

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